The present invention is related to a shift controlling method of a transmission, and more particularly, to a shift controlling method of a transmission that detects an operation condition of a shift lever, drives an actuator based on the detection result, and switches a gear range of the transmission.
An automatic transmission of a vehicle shifts gears based on the speed, the opened degree of the throttle valve, and other parameters. A driver operates a shift lever of a shift device that is mechanically connected to a manual valve of an automatic transmission to select a gear range, such as a P (parking) range, an R (reverse) range, an N (neutral) range, a D (drive) range. The mechanical connection of the automatic transmission and the shift device limits the position where the shift lever of the shift device is arranged. Therefore, in the prior art, the shift lever is arranged near the automatic transmission, for example, on a floor or on a steering column.
A shift-by-wire type shift device that electrically shifts ranges has been proposed. For example, Japanese Laid-Open Patent Publication No. 10-103465 describes a controller of an automatic transmission. When a shift position sensor electrically detects the position of the shift lever, in response to the detection signal, the controller drives a range shifting motor that receives electric power from a battery or an alternator. The power moves a manual valve of the automatic transmission and shifts the gear range. Because the shift lever is not mechanically connected to the manual valve in this controller, the position of the shift device is not limited, and other on-vehicle equipment may be arranged freely.
However, the employment of the controller results in the following shortcoming. When the engine is running, the motor is provided with electromotive force of the alternator, which is connected to the crankshaft. Therefore, the motor shifts the gear range even if a terminal of the battery falls off when the vehicle is moving or if the battery is not functioning normally, such as when the battery power becomes insufficient. However, if the engine stops when the battery is not functioning normally, the rotation of the alternator stops. This stops the generation of electricity. As a result, the motor stops functioning and the gear range cannot be shifted.
For example, if the engine is stopped when a gear range other than the P range (e.g., the N range) is selected and the driver then selects the P range with the shift lever, the driver would believe that a parking lock mechanism is functioning since the shift lever is located at the P range. However, the manual valve of the automatic transmission is actually not moved and the gear range is not shifted to the P range. Therefore, the parking lock mechanism is not functioning and the drive wheels are not locked. If the driver goes away from the vehicle in this condition, the vehicle may start to move depending on the circumstances of where the vehicle is parked without the driver knowing. This problem occurs not only with automatic transmissions but also with manual transmissions that employ shift-by-wire systems.
It is an object of the present invention to provide a shift controlling method of a transmission that prevents the gear range from being maintained in a range other the parking range when a battery is not functioning normally.
It is a further object of the present invention to provide a shift controlling method of a transmission that prevents a driver from going away from a vehicle when the gear range is not shifted to the parking range when the battery is not functioning normally.
To achieve the above object, the present invention provides a method for controlling gear shifting of a transmission connected to an engine of a vehicle. The transmission is supplied with electric power from a battery or an alternator, which is connected to the engine, and drives an actuator based on manipulation of a shifting member by a driver to shift gear ranges of the transmission. The transmission has an output shaft that becomes difficult to rotate if a predetermined range is selected when the engine stops running. The method includes determining whether a gear range differing from the predetermined range is selected by the manipulation of the shifting member when the vehicle stops traveling, and forcibly shifting the gear range of the transmission to the predetermined range when a gear range differing from the predetermined range is selected by driving the actuator with electric power supplied from the alternator.
A further perspective of the present invention is a method for controlling gear shifting of a transmission connected to an engine of a vehicle. The transmission is supplied with electric power from a battery or an alternator, which is connected to the engine, and drives an actuator based on manipulation of a shifting member by a driver to shift gear ranges of the transmission. The transmission has an output shaft that becomes difficult to rotate if a predetermined range is selected when the engine stops running. The method includes detecting the condition of the battery, determining whether a gear range differing from the predetermined range is selected by the manipulation of the shifting member when the vehicle stops traveling, and prohibiting the stopping of the engine when, based on the condition of the battery, the battery does not supply enough electric power to drive the actuator and a gear range differing from the predetermined range is selected.
A further perspective of the present invention is a controller for controlling gear shifting of a transmission connected to an engine of a vehicle. The controller is supplied with electric power from a battery or an alternator, which is connected to the engine, and drives an actuator based on manipulation of a shifting member by a driver to shift gear ranges of the transmission. The transmission has an output shaft that becomes difficult to rotate if a predetermined range is selected when the engine stops running. The controller includes a control unit for determining whether a gear range differing from the predetermined range is selected by the manipulation of the shifting member when the vehicle stops traveling. The control unit forcibly shifts the gear range of the transmission to the predetermined range when a gear range differing from the predetermined range is selected by driving the actuator with electric power supplied from the alternator.
A further perspective of the present invention is a controller for controlling gear shifting of a transmission connected to an engine of a vehicle. The controller is supplied with electric power from a battery or an alternator, which is connected to the engine, and drives an actuator based on manipulation of a shifting member by a driver to shift gear ranges of the transmission. The transmission has an output shaft that becomes difficult to rotate if a predetermined range is selected when the engine stops running. The controller includes a control unit for detecting the condition of the battery, determining whether a gear range differing from the predetermined range is selected by the manipulation of the shifting member when the vehicle stops traveling, and prohibiting the stopping of the engine when, based on the condition of the battery, the battery does not supply enough electric power to drive the actuator and a gear range differing from the predetermined range is selected.
Other aspects and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention